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Unit 3: Nanomaterials and Composites - Practice Quiz

CHE124 — Engineering Chemistry 60 Questions
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1 Nanomaterials are materials that have at least one dimension in the size range of:

introduction to nanomaterials Easy
A. 1 to 100 nm
B. 1 to 100 m
C. 100 to 500 nm
D. 1 to 100 mm

2 As particle size decreases to the nanoscale, the surface area to volume ratio:

introduction to nanomaterials Easy
A. Increases
B. Becomes zero
C. Decreases
D. Remains constant

3 A quantum dot, in which all three dimensions are at the nanoscale, is classified as which type of nanomaterial?

classification of nanomaterials based on dimensionality (0D, 1D, 2D, and 3D) Easy
A. 3D
B. 0D
C. 1D
D. 2D

4 Nanowires and nanotubes, which have two dimensions at the nanoscale and one that is larger, are classified as:

classification of nanomaterials based on dimensionality (0D, 1D, 2D, and 3D) Easy
A. 0D
B. 2D
C. 1D
D. 3D

5 Graphene, a single sheet with only its thickness at the nanoscale, is an example of a:

classification of nanomaterials based on dimensionality (0D, 1D, 2D, and 3D) Easy
A. 1D nanomaterial
B. 2D nanomaterial
C. 0D nanomaterial
D. 3D nanomaterial

6 The fullerene commonly known as a buckyball has the chemical formula:

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Easy
A.
B.
C.
D.

7 Graphene consists of carbon atoms arranged in a:

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Easy
A. Cubic crystal lattice
B. Body-centered lattice
C. Single-layer honeycomb lattice
D. Random amorphous network

8 A carbon nanotube can be visualized as which of the following?

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Easy
A. A chain of individual atoms
B. A diamond crystal wire
C. A rolled-up sheet of graphene
D. A stacked pile of fullerenes

9 The change in properties of nanomaterials as their size decreases is referred to as:

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Easy
A. Density effect
B. Bulk effect
C. Thermal drift
D. Size-dependent effect

10 Gold nanoparticles often appear red rather than the golden color of bulk gold. This is an example of a size-dependent:

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Easy
A. Magnetic property
B. Thermal property
C. Acoustic property
D. Optical property

11 Breaking down bulk material into nanoscale particles is characteristic of which synthesis approach?

methods of nanomaterial synthesis: top-down and bottom-up approaches Easy
A. Self-assembly
B. Top-down
C. Bottom-up
D. Sol-gel

12 Building nanomaterials by assembling atoms or molecules together is known as the:

methods of nanomaterial synthesis: top-down and bottom-up approaches Easy
A. Etching approach
B. Top-down approach
C. Ball milling approach
D. Bottom-up approach

13 Which of the following is an example of a top-down synthesis method?

methods of nanomaterial synthesis: top-down and bottom-up approaches Easy
A. Self-assembly
B. Chemical vapor deposition
C. Sol-gel process
D. Ball milling

14 Nanomaterials are effective catalysts mainly because they provide:

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Easy
A. A large surface area
B. Reduced reactivity
C. A lower melting point
D. Higher electrical resistance

15 In the biomedical field, nanomaterials are widely used for:

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Easy
A. Road construction
B. Making cement
C. Water pipe insulation
D. Targeted drug delivery

16 Nanomaterials are used in energy technologies such as supercapacitors mainly to improve:

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Easy
A. Corrosion rate
B. Charge storage capacity
C. Material weight
D. Manufacturing cost

17 A composite material is made by combining:

fundamental concepts of composite materials Easy
A. Two identical metals
B. Only gases
C. Two or more distinct materials
D. A single pure element

18 In a composite material, the continuous phase that holds the reinforcement together is called the:

role of matrix and reinforcement, composition, structure, and characteristic properties of composites Easy
A. Reinforcement
B. Filler particle
C. Fiber
D. Matrix

19 A composite reinforced with long strands of glass or carbon is classified as a:

classification of composites based on reinforcement type, including particulate composites, fiber-reinforced composites, and structural composites Easy
A. Fiber-reinforced composite
B. Metal matrix composite
C. Laminar composite
D. Particulate composite

20 Fiber-reinforced composites are widely used in the aerospace industry mainly because they are:

Engineering applications of composites Easy
A. Soft and elastic
B. Heavy and brittle
C. Cheap and dense
D. Strong and lightweight

21 A material is generally classified as a nanomaterial when at least one of its dimensions falls in the range of:

introduction to nanomaterials Medium
A. – nm
B. – mm
C. – nm
D. – m

22 The dramatic change in properties of nanomaterials compared to bulk materials is primarily attributed to:

introduction to nanomaterials Medium
A. High surface-area-to-volume ratio and quantum effects
B. Reduced number of atoms per unit cell
C. Higher melting point of the bulk phase
D. Increased density of the material

23 A quantum dot with all three dimensions confined to the nanoscale is classified as:

classification of nanomaterials based on dimensionality (0D, 1D, 2D, and 3D) Medium
A. 3D nanomaterial
B. 1D nanomaterial
C. 0D nanomaterial
D. 2D nanomaterial

24 A nanowire has two dimensions confined to the nanoscale while one dimension is extended. It is therefore a:

classification of nanomaterials based on dimensionality (0D, 1D, 2D, and 3D) Medium
A. 1D nanomaterial
B. 3D nanomaterial
C. 2D nanomaterial
D. 0D nanomaterial

25 Graphene is best classified under which dimensional category of nanomaterials?

classification of nanomaterials based on dimensionality (0D, 1D, 2D, and 3D) Medium
A. 0D nanomaterial
B. 3D nanomaterial
C. 1D nanomaterial
D. 2D nanomaterial

26 The fullerene (buckyball) consists of carbon atoms arranged as:

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Medium
A. hexagons and pentagons
B. hexagons only
C. hexagons and pentagons
D. pentagons only

27 In graphene, each carbon atom is bonded to three neighbors using which hybridization?

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Medium
A.
B.
C.
D.

28 Whether a single-walled carbon nanotube behaves as a metal or a semiconductor is primarily determined by its:

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Medium
A. Purity of synthesis
B. Length
C. Chirality (rolling angle)
D. Color under light

29 When the size of a semiconductor nanoparticle decreases, its band gap generally:

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Medium
A. Increases due to quantum confinement
B. Remains constant
C. Becomes zero
D. Decreases due to quantum confinement

30 Gold nanoparticles appear ruby red in colloidal solution rather than golden due to:

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Medium
A. Change in atomic number
B. Oxidation to gold oxide
C. Surface plasmon resonance
D. Increased density of gold

31 The melting point of a metal nanoparticle compared to its bulk value typically:

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Medium
A. Doubles at the nanoscale
B. Increases as size decreases
C. Stays exactly the same
D. Decreases as size decreases

32 Which of the following is a top-down method of nanomaterial synthesis?

methods of nanomaterial synthesis: top-down and bottom-up approaches Medium
A. Self-assembly of molecules
B. Sol-gel process
C. Chemical vapour deposition
D. Ball milling

33 The sol-gel and chemical vapour deposition methods are examples of which synthesis approach?

methods of nanomaterial synthesis: top-down and bottom-up approaches Medium
A. Mechanical grinding approach
B. Bottom-up approach
C. Lithographic etching approach
D. Top-down approach

34 A key advantage of bottom-up synthesis over top-down methods is:

methods of nanomaterial synthesis: top-down and bottom-up approaches Medium
A. Inability to form ordered structures
B. Higher production of surface defects
C. Better control over size and uniformity of nanostructures
D. Requirement of only bulk raw material

35 Nanomaterials greatly enhance catalytic activity mainly because they provide:

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Medium
A. A larger active surface area per unit mass
B. A lower number of active sites
C. A higher melting point for reactions
D. A thicker diffusion barrier

36 In targeted drug delivery, nanoparticles are especially useful because they can:

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Medium
A. Dissolve only in metallic tissues
B. Carry drugs to specific cells and release them in a controlled way
C. Increase the drug's molecular weight for stability
D. Convert drugs into inert gases

37 Nanostructured electrodes improve supercapacitor performance primarily by:

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Medium
A. Blocking ion movement in the electrolyte
B. Eliminating the need for an electrolyte
C. Reducing the operating voltage window
D. Increasing surface area for charge storage

38 A composite material is best defined as:

fundamental concepts of composite materials Medium
A. A homogeneous solution of two liquids
B. A single-phase alloy of two metals
C. A pure element refined to nanoscale purity
D. A combination of two or more distinct materials with a recognizable interface

39 In a fiber-reinforced composite, the primary role of the matrix is to:

role of matrix and reinforcement Medium
A. Provide the composite's electrical conductivity
B. Bind fibers together and transfer load to them
C. Carry most of the applied load directly
D. Act as the sole strengthening phase

40 In most fiber-reinforced composites, the reinforcement phase mainly provides:

role of matrix and reinforcement Medium
A. Corrosion resistance only
B. Electrical grounding only
C. Thermal insulation only
D. Strength and stiffness

41 A material is described as having all three of its external dimensions above the nanoscale, but it is composed internally of nanoscale grains, layers, or clusters. How should this material be classified and why?

classification of nanomaterials based on dimensionality (0D, 1D, 2D, and 3D) Hard
A. 0D nanomaterial, because the internal clusters are quantum dots
B. 1D nanomaterial, because the grains align into nanoscale channels
C. 2D nanomaterial, because layered internal features dominate its behavior
D. 3D nanomaterial, because bulk dimensions exceed 100 nm while nanoscale features exist internally

42 For a semiconductor quantum dot, the effective band gap increases as particle size decreases. If the confinement energy scales approximately as where is the diameter, reducing the diameter from to changes the confinement contribution by what factor?

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Hard
A. Increases by a factor of
B. Increases by a factor of
C. Increases by a factor of
D. Decreases by a factor of

43 A single-walled carbon nanotube is defined by chiral indices . Which condition determines whether the nanotube behaves as a metallic conductor?

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Hard
A. only (armchair) with no other cases
B. is a multiple of
C. is even
D. is a multiple of

44 In (buckminsterfullerene), the structure consists of 12 pentagons and 20 hexagons. Using Euler's rule for a closed cage of carbons, why must exactly 12 pentagons be present regardless of the number of hexagons?

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Hard
A. Hexagons alone can close a cage, so 12 pentagons is arbitrary
B. The number of pentagons equals half the number of hexagons
C. Pentagons must equal the number of vertices divided by 5
D. Euler's polyhedron formula fixes pentagons at 12 to close the cage independent of hexagon count

45 A researcher needs monodisperse nanoparticles with atomically precise control over composition and minimal defects. Which pairing of approach and reasoning is most appropriate?

methods of nanomaterial synthesis: top-down and bottom-up approaches Hard
A. Top-down, because lithography avoids all surface defects
B. Bottom-up, because assembly from atoms/molecules allows fine control over size and structure
C. Bottom-up, because it always produces larger particles faster
D. Top-down, because milling gives precise atomic control

46 The fraction of atoms on the surface of a nanoparticle rises sharply as size decreases. This surface-to-volume effect most directly explains which observed behavior?

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Hard
A. Constant catalytic activity irrespective of size
B. Depression of the melting point compared to the bulk material
C. Complete loss of crystallinity in all nanoparticles
D. Increase in the melting point above the bulk value

47 Gold nanoparticles appear ruby-red in colloidal suspension rather than golden. Which phenomenon is chiefly responsible for this size-dependent optical behavior?

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Hard
A. Total internal reflection within each particle
B. Fluorescence from d-band transitions
C. Localized surface plasmon resonance absorbing green light
D. Rayleigh scattering of blue light only

48 Nanostructured electrodes greatly boost supercapacitor performance mainly because of which combined effect?

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Hard
A. Larger grain size increases Faradaic reactions and lowers resistance
B. Increased electrode thickness shortens the electrolyte path
C. High surface area increases charge storage while short diffusion paths speed ion transport
D. Reduced surface area concentrates charge at fewer sites

49 For a continuous fiber-reinforced composite loaded parallel to the fibers (isostrain condition), the longitudinal modulus follows the rule of mixtures. If , , and fiber volume fraction , what is ?

fundamental concepts of composite materials Hard
A.
B.
C.
D.

50 In a fiber-reinforced composite under longitudinal tension, what is the primary mechanical role of the matrix phase?

role of matrix and reinforcement Hard
A. Acting as the main crack-initiation site by design
B. Providing the highest stiffness in the composite
C. Transferring applied load to the fibers via shear and protecting them
D. Carrying the majority of the tensile load directly

51 A continuous fiber composite is loaded transverse to the fibers (isostress condition). Using the inverse rule of mixtures with , , , the transverse modulus is closest to which value?

fundamental concepts of composite materials Hard
A.
B.
C.
D.

52 A sandwich panel with stiff face sheets bonded to a lightweight honeycomb core is best classified as which type of composite, and what governs its bending stiffness?

classification of composites based on reinforcement type, including particulate composites, fiber-reinforced composites, and structural composites Hard
A. Dispersion-strengthened composite; stiffness set by dispersoid size
B. Structural composite; bending stiffness rises with face-sheet separation by the core
C. Fiber-reinforced composite; stiffness set by fiber orientation
D. Particulate composite; stiffness set by particle volume fraction

53 Why do nanoparticle catalysts often show far higher activity per unit mass than their bulk counterparts?

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Hard
A. Smaller particles reduce the total surface area exposed to reactants
B. A high fraction of low-coordination surface atoms provides abundant active sites
C. Nanoparticles eliminate the need for reactant adsorption
D. Bulk atoms in the interior are the dominant catalytic sites

54 Graphene exhibits extremely high charge-carrier mobility. Which feature of its electronic structure is most directly responsible for its charge carriers behaving as massless Dirac fermions?

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Hard
A. Linear energy-momentum dispersion at the Dirac points where bands touch
B. A large parabolic band gap at the K points
C. Strong ionic bonding between carbon layers
D. Localized flat bands across the Brillouin zone

55 Chemical vapor deposition (CVD) is widely used to grow high-quality graphene and carbon nanotubes. Which classification and rationale correctly describe CVD?

methods of nanomaterial synthesis: top-down and bottom-up approaches Hard
A. Top-down, because a bulk carbon block is etched into sheets
B. Bottom-up, because it grinds precursors into fine powder
C. Bottom-up, because solid material is assembled from gas-phase precursor molecules
D. Top-down, because it relies on mechanical exfoliation

56 A nanowire and a graphene sheet differ in how many dimensions are confined to the nanoscale. Which statement correctly pairs each with its dimensional class?

classification of nanomaterials based on dimensionality (0D, 1D, 2D, and 3D) Hard
A. Nanowire is 1D (two dimensions confined); graphene is 2D (one dimension confined)
B. Nanowire is 0D; graphene is 3D
C. Nanowire is 2D; graphene is 1D
D. Both are 0D because carriers are fully confined

57 In targeted drug delivery, nanoparticles can accumulate preferentially in tumor tissue even without active targeting ligands. Which effect explains this passive accumulation?

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Hard
A. Covalent bonding of nanoparticles to healthy tissue only
B. Enhanced permeability and retention due to leaky tumor vasculature and poor lymphatic drainage
C. Magnetic attraction of all nanoparticles to cancer cells
D. Active transport by tumor-cell ion pumps selecting nanoparticles

58 A designer wants a composite with high specific strength (strength-to-weight ratio) for aerospace panels. Comparing options, why is a carbon-fiber/epoxy composite generally preferred over a steel component of equal strength?

composition, structure, and characteristic properties of composites Hard
A. Its low density gives higher strength-to-weight ratio at comparable strength
B. Its isotropic behavior guarantees equal properties in all directions
C. Its higher density improves fatigue resistance directly
D. Its metallic matrix conducts heat better than steel

59 Individual defect-free carbon nanotubes show very high thermal conductivity, yet bulk mats of nanotubes conduct heat poorly. What primarily accounts for this discrepancy?

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Hard
A. A drop in intrinsic conductivity of each tube when bundled
B. Phonon scattering at tube-tube junctions and interfacial thermal resistance in the mat
C. Electron scattering replacing phonon transport in mats
D. Complete loss of the crystalline structure upon bundling

60 Fiber-reinforced polymer (FRP) bars are increasingly used instead of steel rebar in bridge decks exposed to de-icing salts. Which property advantage most directly justifies this choice?

Engineering applications of composites Hard
A. Magnetic behavior that repels salt ions
B. Corrosion resistance, since FRP does not rust like steel in chloride environments
C. Higher thermal conductivity to melt ice on the deck
D. Higher ductility than steel allowing large plastic deformation
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